I personally believe the best genre can vary between action roleplay and a first person shooter. These two genres are so much fun for there own reasons. In action role-play you have such an open world that makes it feel like you are actually the character playing. And in Fps shooters they are so fun for the sheer point of strategy and plays.More info on Outer-Worlds
Of the two genres action role-play and fps the best games are Outerworlds(action role -play) and Overwatch(fps). Personally I enjoy outerworlds because you can play it again and again and get different outcomes. In Outerworlds you can be a super nice hero or a crazy phyco. Not to mention the setting is so cool and you feel like you are in another universe doing anything you want.
The Game Overwatch is tied with Outerworlds for the best game but looses for the genre. While fps games are fun they seem to get repetative if they aren't mixed in with a roleplay like outerworlds. In Overwatch there are so many characters but much like anygame it can get a little boring if you can't entertain yourself.
I personally love apex, it is a great game,I could easily say my favorite but you easily get burnout much like overwatch.